Engines, such as internal combustion engines, often include an aftertreatment system for reducing and converting particulate matter or nitrogen oxides (NOx) that may be present in an exhaust gas flow, to comply with emission regulation standards. The aftertreatment system may include a selective catalytic reduction (SCR) module that reduces a concentration of NOx in the exhaust gas flow. Before the exhaust gas flow enters an SCR module, a reductant is typically dosed into the exhaust gas flow passing through the aftertreatment system.
Performance of such an SCR module is affected by adequate conversion of the reductant into reducing agents. Under certain operating conditions, such as high dosing rate of the reductant, low exhaust gas temperature, and flow rate of the exhaust gas flow, reductant mass deposits can form on surfaces of the aftertreatment system and/or the SCR module, which in turn results in poor NOx conversion, suboptimal performance of the SCR module, and sometimes even failure of the engine system. To reduce such deposits formed in the SCR module, periodic regeneration of the SCR catalyst may be necessary.
U.S. Pat. No. 8,739,517 describes a method for controlling regeneration of an SCR catalyst. The method includes coordinating the regeneration duration and temperature (e.g., longer/shorter regenerations and/or lower/higher temperatures) to the urea deposit loading. In this way, improved regeneration may be achieved due to the particular nature of urea deposits on SCR catalysts.